ES2946133T3 - Manufacturing procedure of an aluminum alloy part - Google Patents

Abstract

The invention refers to a manufacturing process for a part (20) that comprises the formation of successive metal layers (201... 20n) superimposed on each other, each layer being formed by depositing a filler metal (15, 25), providing energy to the filler metal in such a way that it melts and when solidified constitutes said layer, the method being characterized because the filler metal (15, 25) is an aluminum alloy that comprises the following alloying elements (in % by weight): - Zr: 0.5 to 2.5%, preferably, according to a first variant, 0.8 to 2.5%, more preferably 1 to 2.5%, even more preferably 1.3 to 2.5%; or preferably, according to a second variant, from 0.5 to 2%, more preferably from 0.6 to 1.8%, more preferably from 0.6 to 1.6%, more preferably from 0.7 to 1.5 %, more preferably 0.8 to 1.5%, more preferably 0.9 to 1.5%, even more preferably 1 to 1.4%; - Fe: 0% to 3%, preferably 0.5 to 2.5%; preferably, according to a first variant, from 0.8 to 2.5%, preferably from 0.8 to 2%, more preferably from 0.8 to 1.2%; or preferably, according to a second variant, from 1.5 to 2.5%, preferably from 1.6 to 2.4%, more preferably from 1.7 to 2.3%; - optionally Yes: <= 0.3%, preferably < 0.2%, more preferably < 0.1%; - optionally Cu: <= 0.5%, preferably 0.05 to 0.5%, preferably 0.1 to 0.4%; - optionally Mg: <= 0.2%, preferably < 0.1%, preferably < 0.05%; - other alloying elements: < 0.1% individually and in total < 0.5%; - impurities: < 0.05% individually and in total < 0.15%; the rest is aluminum. more preferably 1.7 to 2.3%; - optionally Yes: <= 0.3%, preferably < 0.2%, more preferably < 0.1%; - optionally Cu: <= 0.5%, preferably 0.05 to 0.5%, preferably 0.1 to 0.4%; - optionally Mg: <= 0.2%, preferably < 0.1%, preferably < 0.05%; - other alloying elements: < 0.1% individually and in total < 0.5%; - impurities: < 0.05% individually and in total < 0.15%; the rest is aluminum. more preferably 1.7 to 2.3%; - optionally Yes: <= 0.3%, preferably < 0.2%, more preferably < 0.1%; - optionally Cu: <= 0.5%, preferably 0.05 to 0.5%, preferably 0.1 to 0.4%; - optionally Mg: <= 0.2%, preferably < 0.1%, preferably < 0.05%; - other alloying elements: < 0.1% individually and in total < 0.5%; - impurities: < 0.05% individually and in total < 0.15%; the rest is aluminum. (Automatic translation with Google Translate, without legal value)

Description

DESCRIPTION

Manufacturing procedure of an aluminum alloy part

technical field

The technical field of the invention is a process for manufacturing an aluminum alloy part, which implements an additive manufacturing technique.

prior art

Since the 1980s, additive manufacturing techniques have been developed. They consist of shaping a piece by adding matter, which is the opposite of machining techniques, which aim to remove matter. Previously limited to prototyping, additive manufacturing is currently operational to mass-produce industrial products, including metal parts.

The expression "additive manufacturing" is defined according to the French standard XP E67-001 as a "set of procedures that make it possible to manufacture, layer by layer, by adding matter, a physical object from a digital object". ASTM F2792 (January 2012) also defines additive manufacturing. Different modalities of additive manufacturing are also defined and described in the ISO/ASTM 17296-1 standard. The use of additive manufacturing to make an aluminum part with low porosity has been described in document WO2015006447. The application of successive layers is generally carried out by applying a so-called filler material, and then melting or sintering the filler material, with the help of an energy source such as a laser beam, electron beam, or plasma torch. or electric arc. Regardless of the additive manufacturing modality applied, the thickness of each added layer is of the order of a few tens or hundreds of micrometers.

Other additive manufacturing methods can be used. Mention is made, for example, and without limitation, the melting or sintering of a filler material that takes the form of a powder. It can be fusion or laser sintering. Patent application US-20170016096 describes a process for manufacturing a piece by means of localized fusion obtained by exposing a powder to an energy beam of the electron beam or laser beam, the process also being called by the acronyms in English SLM , which stands for “Selective Laser Melting”, or EBM, which stands for “Electron Beam Melting”.

The mechanical properties of the aluminum parts obtained through additive manufacturing depend on the alloy that forms the filler metal and, more precisely, on its composition, as well as on the heat treatments applied after the implementation of additive manufacturing. The applicant has determined an alloy composition which, when used in an additive manufacturing process, makes it possible to obtain parts with notable mechanical performance, without it being necessary to implement heat treatments of the dissolving and tempering type. In addition, the parts used have interesting properties of thermal conductivity or electrical conductivity. This allows to diversify the possibilities of applications of these parts.

Description of the invention

A first object of the invention is a method for manufacturing a part, which comprises a formation of successive metal layers, superimposed one on the other, each layer being formed by deposition of a filler metal, the filler metal being subjected to a filler. of energy, so that it melts and forms, when solidified, said layer, the procedure being characterized in that the filler metal is an aluminum alloy that comprises the following alloy elements (% by weight):

- Zr: from 0.5% to 2.5%, preferably, according to a first variant, from 0.8 to 2.5%, more preferably from 1 to 2.5%, even more preferably from 1.3 to 2.5 %; or preferably, according to a second variant, from 0.5 to 2%, more preferably from 0.6 to 1.8%, more preferably from 0.6 to 1.6%, more preferably from 0.7 to 1.5 %, more preferably 0.8 to 1.5%, more preferably 0.9 to 1.5%, even more preferably 1 to 1.4%;

- Fe: from 0% to 3%, preferably from 0.5% to 2.5%; preferably, according to a first variant, from 0.8 to 2.5%, preferably from 0.8 to 2%, more preferably from 0.8 to 1.2%; or preferably, according to a second variant, from 1.5 to 2.5%, preferably from 1.6 to 2.4%, more preferably from 1.7 to 2.3%;

- optionally, Si: ≤ 0.3%, preferably ≤ 0.2%, more preferably ≤ 0.1%;

- optionally, Cu: ≤ 0.5%, preferably 0.05 to 0.5%, preferably 0.1 to 0.4%;

- optionally, Mg: ≤ 0.2%, preferably ≤ 0.1%, preferably < 0.05%;

- other alloying elements < 0.1% individually, and in total <0.5%;

- impurities: <0.05% individually, and in total <0.15%;

the rest, aluminum.

Among the other alloying elements, mention is made, for example, of Cr, V, Ti, Mn, Mo, W, Nb, Ta, Sc, Ni, Zn, Hf, Nd, Ce, Co, La, Ag, Li, Y , Yb, Er, Sn, In, Sb, Sr, Ba, Bi, Ca, P, B and/or Mischmetal.

Preferably, the procedure can comprise the following characteristics, taken in isolation or according to technically feasible combinations:

- Zr: from 0.8 to 2.5%, or preferably from 1% to 2.5%, or more preferably from 1.2% to 2.5%, or more preferably from 1.3% to 2.5 %, or more preferably from 1.5% to 2.5%;

- Zr: from 0.5 to 2%, more preferably from 0.6 to 1.8%, more preferably from 0.6 to 1.6%, more preferably from 0.7 to 1.5%, more preferably from 0.8 to 1.5%, more preferably 0.9 to 1.5%, even more preferably 1 to 1.4%;

- Fe: from 0.5% to 2.5%, or from 0.5% to 2%; preferably 0.8 to 2.5%, preferably 0.8 to 2%, more preferably 0.8 to 1.2%;

- Fe: from 0.5% to 2.5%, or from 0.5% to 2%; preferably 1.5 to 2.5%, preferably 1.6 to 2.4%, more preferably 1.7 to 2.3%;

- Yes: <0.2%, and preferably <0.1%;

- If > 0.01%, even > 0.05%;

- Cu: from 0.05% to 0.5%, preferably from 0.1 to 0.4%;

- Zr: from 0.5% to 2.5%, and Fe > 1%;

- Zr: from 0.5% to 2.5%, and Fe < 1%;

- the mass fraction of each of the other alloying elements is strictly less than 500 ppm, 300 μm, 200 ppm, even 100 ppm;

- the mass fraction of each impurity is strictly less than 300 μm, at 200 ppm, even at 100 ppm;

- the alloy does not contain Cr, V, Mn, Ti, Mo, or according to a mass fraction less than 500 ppm, at 300 ppm, at 200 ppm even less than 100 ppm.

According to a variant, the alloy used according to the present invention comprises Cu, according to a mass fraction of 0.05% to 0.5%, preferably 0.1 to 0.4%.

Each layer can concretely describe a pattern defined from a digital model.

The method can comprise, after the formation of the layers, that is to say, after the formation of the final part, an application of at least one heat treatment. The heat treatment can be or comprise tempering or annealing. It can also include dissolving and tempering, although it is preferred to avoid them. It can also include hot isostatic compression.

In order to privilege the mechanical properties, the heat treatment can be carried out:

- at a temperature higher than 400°C, in which case the duration of the heat treatment is between 0.1 h and 10 h;

- or at a temperature between 300 0C and 400 0C, in which case the duration of the heat treatment is between 0.5 h and 100 h.

In order to privilege the thermal or electrical conduction properties, the heat treatment can be carried out at a temperature greater than or equal to 350 0C, or 400 0C, or for a duration of 90 to 200 h, so as to obtain a thermal conductivity or optimal electrical. For example, a temperature of 380 to 470 0C, and a duration of 90 to 110 h.

According to an advantageous embodiment, the method does not include any tempering after the formation of the layers, that is to say, after the formation of the final part, or after the heat treatment. Therefore, preferably, the process does not comprise any step of putting into solution, followed by quenching.

According to one embodiment, the filler metal is in the form of a powder, whose exposure to a beam of light or charged particles results in localized melting, followed by solidification, so that a solid layer is formed. According to another embodiment, the filler metal comes from a filler wire, whose exposure to an electric arc results in a localized melting, followed by solidification, so that a solid layer is formed. A second object of the invention is a metal part, obtained after applying a procedure according to the first object of the invention.

A third object of the invention is a filler material, specifically, a filler wire or a powder, intended to be used as filler material in an additive manufacturing process, characterized in that it consists of an aluminum alloy, which comprises the following alloying elements (% by weight):

- Zr: from 0.5% to 2.5%, preferably, according to a first variant, from 0.8 to 2.5%, more preferably from 1 to 2.5%, even more preferably from 1.3 to 2.5 %; or preferably, according to a second variant, from 0.5 to 2%, more preferably from 0.6 to 1.8%, more preferably from 0.6 to 1.6%, more preferably from 0.7 to 1.5 %, more preferably 0.8 to 1.5%, more preferably 0.9 to 1.5%, even more preferably 1 to 1.4%; - Fe: from 0% to 3%, preferably from 0.5% to 2.5%; preferably, according to a first variant, from 0.8 to 2.5%, preferably from 0.8 to 2%, more preferably from 0.8 to 1.2%; or preferably, according to a second variant, from 1.5 to 2.5%, preferably from 1.6 to 2.4%, more preferably from 1.7 to 2.3%;

- optionally, Si: <0.3%, preferably <0.2%, more preferably <0.1%;

- optionally, Cu: <0.5%, preferably from 0.05 to 0.5%, preferably from 0.1 to 0.4%;

- optionally, Mg: <0.2%, preferably <0.1%, preferably <0.05%;

- other alloying elements < 0.1% individually, and in total < 0.5%;

- impurities: <0.05% individually, and in total <0.15%;

the rest, aluminum.

The aluminum alloy that forms the filler material can have the characteristics described in relation to the first object of the invention.

The filler material can be in the form of a powder. The powder can be such that at least 80% of the particles that make up the powder have an average size in the following range: 5 µm to 100 µm, preferably 5 to 25 µm, or 20 to 60 µm.

When the filler material is in the form of a wire, the diameter of the wire can be specifically from 0.5 mm to 3 mm, and preferably from 0.5 mm to 2 mm, and more preferably from 1 mm to 2mm.

Another object of the invention is the use of a powder or a filler wire, as described above and in the rest of the description, in a manufacturing process chosen from: cold spraying (CSC), spray deposition laser fusion (LMD), additive friction manufacturing (AFS), spark plasma sintering (FAST), or rotary friction welding (IRFW), preferably cold spraying (CSC).

Other advantages and characteristics will emerge more clearly from the following description of particular embodiments of the invention, provided as non-limiting examples, and represented in the figures indicated below.

figures

[Figure 1] Figure 1 is a schematic illustrating an SLM-type additive manufacturing process.

[Figure 2] Figure 2 illustrates tensile and electrical conduction properties determined through the experimental tests of Example 1, from samples made by practicing an additive manufacturing process according to the invention.

[Figure 3] Figure 3 is a schematic illustrating a WAAM-type additive manufacturing process.

[Figure 4] Figure 4 is a schematic of the test tube used according to the examples.

[Figure 5] Figure 5 is a schematic of the second test pieces of Example 1.

[Figure 6] Figure 6 illustrates tensile and electrical conduction properties determined through the experimental tests of Example 2, from samples made by practicing an additive manufacturing process according to the invention.

Description of particular embodiments

In the description, unless otherwise stated:

- the designation of aluminum alloys is according to the nomenclature of The Aluminum Association;

- The contents of chemical elements are designated in %, and represent mass fractions. The notation x% -y% means greater than or equal to x%, and less than or equal to y%.

By impurity, we mean chemical elements present in the alloy unintentionally.

Figure 1 schematizes the operation of an additive manufacturing procedure of the selective laser melting type (Selective Laser Melting, or SLM). The filler metal 15 is in the form of a powder arranged on a support 10. An energy source, in this case a laser source 11, emits a laser beam 12. The laser source is coupled to the filler material by means of an optical system 13, the movement of which is determined as a function of a digital model M. The laser beam 12 propagates along a propagation axis Z, and follows a movement along an XY plane. , which describes a pattern that depends on the digital model. The plane is, for example, perpendicular to the axis of propagation Z. The interaction of the laser beam 12 with the dust 15 generates a selective melting of the latter, followed by a solidification, which results in the formation of a layer 20 ¹ . ..20 ⁿ . When a layer has been formed, it is covered with filler metal powder, and another layer is formed, superimposed on the layer previously made. The thickness of the powder forming a layer can be, for example, from 10 to 200 μm.

For aluminum alloys, the support 10, or the plate, can be heated up to 350°C. The machines currently available on the market generally offer plate heating up to 200°C. The heating temperature of the plate can be, for example, approximately 50°C, 100°C, 150°C, or 200°C. The heating of the plate allows, generally, to reduce the humidity at the level of the powder bed, and also to reduce the residual stresses in the pieces under manufacture. The level of humidity at the level of the powder bed seems to have a direct effect on the porosity of the final piece. Indeed, it appears that the higher the moisture content of the powder, the higher the porosity of the final part. It should be noted that heating the plate is one of the existing possibilities to carry out hot additive manufacturing. However, the present invention is not limited to the use of this single heating medium. All other heating means can be used in the context of the present invention, for heating and temperature control, for example an infrared lamp. Therefore, the process according to the present invention can be carried out at a temperature ranging up to 350°C.

Dust may have at least one of the following characteristics:

- Average particle size of 5 to 100 μm, preferably 5 to 25 μm, or 20 to 60 μm. The given values mean that at least 80% of the particles have a mean size in the specified range.

- Spherical shape. The sphericity of a powder can be determined, for example, using a morphogranulometer.

- Good pourability. The pourability of a powder can be determined, for example, according to ASTM B213 or ISO 4490:2018. According to ISO 4490:2018, the flow time is preferably less than 50.

- Low porosity, preferably from 0 to 5%, more preferably from 0 to 2%, even more preferably from 0 to 1% by volume. Porosity can be determined specifically by image analysis from light photomicrographs, or by helium pycnometry (see ASTM B923).

- The absence or low amount (less than 10%, preferably less than 5% by volume) of small particles (from 1 to 20% of the average size of the dust), called satellites, which adhere to the larger particles.

The implementation of a method of this type allows a manufacturing of parts according to a high throughput, which can reach, or even exceed, 40 cm ³ /h.

On the other hand, the applicant has observed that the application of heat treatments of the tempering type can induce a distortion of the piece, due to the sudden variation of the temperature. The distortion of the piece is generally all the more significant, since its dimensions are important. However, the advantage of an additive manufacturing procedure is precisely to obtain a part whose shape, after manufacturing, is final, or almost final. Therefore, the occurrence of significant deformation resulting from heat treatment must be avoided. By almost final, it is understood that a finish machining can be carried out on the part after its manufacture: the part manufactured by additive manufacturing is understood according to its final form, with the exception of finish machining.

Having verified the above, the applicant has searched for an alloy composition, which forms the filler material, which allows obtaining acceptable mechanical properties, without requiring the application of heat treatments, after the formation of the layers, that is, after the formation of the final piece, which run the risk of inducing distortion. Specifically, it is about avoiding heat treatments that involve a sudden variation in temperature. Therefore, the invention makes it possible to obtain, by additive manufacturing, a part whose mechanical properties are satisfactory, in particular as regards the elastic limit. Depending on the type of additive manufacturing process chosen, the filler material can be in the form of a wire or a powder.

The applicant has found that, by limiting the number of elements present in the alloy that have a content of more than 1% by mass, a good compromise between interesting mechanical and thermal properties is obtained. Usually, it is accepted that the addition of elements in the alloy makes it possible to improve certain mechanical properties of the part made by additive manufacturing. By mechanical properties is meant, for example, the yield point or the elongation at break. However, the addition of too great a quantity, or too great a diversity, of chemical alloying elements, can impair the thermal conduction properties of the part resulting from additive manufacturing. Therefore, the use of binary or ternary alloys, in an additive manufacturing procedure, constitutes a promising path in the field of additive manufacturing.

The Applicant has considered that it was useful to obtain a compromise between the number and the quantity of the elements added in the alloy, so as to obtain acceptable mechanical and thermal (or electrical) properties.

The applicant considers that a compromise of this type is obtained by limiting to only one, or two, the number of chemical elements that make up the aluminum alloy that have a mass fraction greater than or equal to 1 %. Therefore, a particularly interesting alloy can be obtained by adding, according to a mass fraction greater than 1%:

- only Zr, in which case the alloy consists essentially of two elements (AI and Zr). For example, Zr: 0.5% to 2.5%, and Fe < 1%;

- or Zr and Fe, in which case the alloy is essentially made up of three elements (AI, Zr and Fe). The presence of Fe in the alloy allows to improve the mechanical properties, whether it is the mechanical properties in hot and cold traction, or the hardness. For example, Zr: 0.5% to 2.5%, and Fe > 1%.

The presence of Zr in the alloy confers a good processability of the alloy, the term processability corresponding to the English designation "processability", which qualifies the ability of an alloy to be formed by an additive manufacturing process. This translates, at the level of a part manufactured by additive manufacturing, in an almost absence of defects, such as cracking, and low porosity. The applicant has verified that a mass fraction of Zr greater than 0.5% confers good processability. An optimal fraction by mass of Zr can be comprised, according to a first variant, from 0.8 to 2.5%, more preferably from 1 to 2.5%, still more preferably from 1.3 to 2.5%; or preferably, according to a second variant, from 0.5 to 2%, more preferably from 0.6 to 1.8%, more preferably from 0.6 to 1.6%, more preferably from 0.7 to 1.5 %, more preferably 0.8 to 1.5%, more preferably 0.9 to 1.5%, even more preferably 1 to 1.4%. When Zr is less than 0.5%, generally the mechanical properties are not enough.

The applicant has observed in an SLM process, and in the presence of Zr, specifically, for a Zr content > 0.5%, throughout the solidification of each layer, equiaxed grains that form under the treatment bead with laser, from primary ZrAb precipitates that form in the liquid. The primary ZrAb precipitates serve as seeds, from which equiaxed aluminum grains are formed. The remainder of the laser treatment bead solidifies into columnar grains that grow from the edge toward the center of the bead, in a radial manner. The higher the Zr content, the larger the equiaxed grain fraction, and the lower the columnar grain fraction. The presence of a sufficient fraction of equiaxed grains is beneficial in avoiding end-solidification cracking.

However, when the Zr content is < 0.5 %, the concentration of primary AbZr precipitates is too low, which leads to the formation of coarse columnar grains that can cross several layers, according to epitaxial growth, advancing in one direction. layer to another. Therefore, the piece obtained is more sensitive to solidification cracking.

This effect of the Zr content on the sensitivity to cracking is specific to additive manufacturing processes with melting of each layer, such as the SLM process. In the case of the non-additive process, such as the classical, so-called quick-setting processes, with compaction and spinning of parts from thin, quickly set strips or powder, parts can be made from alloys with Zr contents < 0.5% , without cracking. Indeed, these processes do not require melting during the shaping stage and are therefore not subject to solidification cracks.

The applicant has also verified that the presence of copper <0.5%, preferably from 0.05 to 0.5%, preferably from 0.1 to 0.4%, makes it possible to improve the mechanical properties and compromise electrical conductivity/ elastic limit after heat treatment.

Preferably, the fraction by mass of Zr is between 0.5% and 2.5%, preferably, according to a first variant, between 0.8% and 2.5%, even between 1% and 2.5%, even from 1.2% to 2.5%, even from 1.3% to 2.5%, even from 1.5% to 2.5%; or preferably, according to a second variant, from 0.5 to 2%, even from 0.6 to 1.8%, even from 0.6 to 1.6%, even from 0.7 to 1.5%, even from 0.8 to 1.5%, even from 0.9 to 1.5%, even from 1 to 1.4%.

When the alloy comprises Fe, the mass fraction of Fe is less than or equal to 3%. It is preferably between 0.5% and 3%, preferably, according to a first variant, between 0.8 and 2.5%, preferably between 0.8 and 2%, more preferably between 0.8 and 1.2%; or preferably, according to a second variant, from 1.5 to 2.5%, preferably from 1.6 to 2.4%, more preferably from 1.7 to 2.3%. An association of Zr and Fe is particularly advantageous, as mentioned above, and is confirmed by experimental tests. The alloy may also comprise other alloying elements, such as Cr, V, Ti, Mn, Mo, W, Nb, Ta, Sc, Ni, Zn, Hf, Nd, Ce, Co, La, Ag, Li, Y, Yb, Er, Sn, In, Sb, Sr, Ba, Bi, Ca, P, B, and/or Mischmetal, based on an individual mass fraction strictly less than 0.1%, preferably less than 500 ppm, and preferably less at 300 ppm, or at 200 ppm, or at 100 ppm. However, some of these alloying elements, in particular Cr, V, Ti and Mo, degrade conductivity. Cu is considered to be less harmful with respect to thermal and/or electrical conductivity.

The addition of Mg, in the absence of a solution-quenching-tempering treatment, would reduce the electrical or thermal conductivity, without having a significant impact on the mechanical properties. Added to this is the tendency to evaporate during the atomization and SLM process, especially for high liquidus alloys, such as those tested in the present invention. Therefore, according to a variant, the alloy used according to the present invention does not contain Mg, or contains it according to an amount of impurity, that is to say, <0.05%.

When the alloy comprises other alloying elements, such as Y, Yb, Er, Sn, In, Sb, they are preferably present according to a mass fraction strictly less than 500 ppm, even strictly less than 300 ppm, even strictly less than 200 ppm or at 100ppm.

It should be noted that, preferably, the alloys according to the present invention are not AA6xxx type alloys, due to the absence of simultaneous addition of Si and Mg in amounts greater than 0.2%.

By way of examples, the aluminum alloy used according to the present invention may comprise:

- 1.52% Zr; Faith at 213 ppm; Yes at 183 ppm; impurities: < 0.05%, each with < 0.15% accumulation of impurities;

- 1.23% Zr; Faith at 0.94%; impurities < 0.05%, each with an accumulation < 0.15%;

- 0.81% Zr; Faith at 1.83%; impurities < 0.05%, each with an accumulation < 0.15%; either

- 1.39% Zr; 0.32% Cu; impurities < 0.05%, each with an accumulation < 0.15%.

experimental examples

Example 1

First tests were carried out using an alloy 1, whose composition by mass measured by ICP comprised: Zr: 1.52%; Faith at 213 ppm; Yes at 183 ppm; impurities: <0.05%, each with <0.15% impurity accumulation.

Test pieces were made by SLM, using a machine of the type EOS290 SLM (supplier EOS). This machine allows the plate on which the pieces are made to be heated up to a temperature of approximately 200 0C. The tests were carried out with a plate heated to approximately 200 0C, but additional tests have shown the good processability of the alloys according to the present invention, at lower plate temperatures, for example, 25 0C, 50 0C, 100 0C , or 150 0C.

The laser power was 370 W. The scanning speed was equal to 1400 mm/s. The separation between two adjacent scan lines, usually designated by the term "separation vector", was 0.11 mm. The layer thickness was 60 μm.

The powder used had a particle size essentially ranging from 3 µm to 100 µm, with a median of 40 µm, a 10% quantile of 16 µm, and a 90% quantile of 79 µm.

First test pieces were made, in the form of solid cylinders vertical (Z direction) with respect to the construction plate that forms the base in the plane (X-Y). The cylinders had a diameter of 11 mm and a height of 46 mm. Second test pieces were made, which took the form of parallelepipeds with dimensions of 12 (X direction) x 45 (Y direction) x 46 (Z direction) mm (see Figure 5). All the pieces were subjected to a relaxation treatment after manufacturing, of SLM for 4 hours at 300 0C.

Some early pieces were subjected to a heat treatment after manufacturing, at 350 0C, 400 0C, or 450 0C, the duration of the treatment ranging from 1 h to 104 h. The set of the first parts (with and without heat treatment after manufacturing) was machined to obtain cylindrical tensile specimens, which had the following characteristics in mm (see Table 1 and Figure 4):

In Figure 4 and Table 1.0 represents the diameter of the central part of the test piece, M the width of the two ends of the test piece, LT the total length of the test piece, R the radius of curvature between the central part and the ends of the test piece, Le the length of the central part of the test piece, and F the length of the two ends of the test piece.

[Table 1]

These cylindrical specimens were subjected to tensile testing at room temperature, according to the NF EN ISO 6892-1 (2009-10) standard.

Some second test pieces were subjected to a heat treatment after manufacture, as described in connection with the first pieces. The second test pieces were subjected to electrical conductivity tests, based on the fact that electrical conductivity evolves in a similar way to thermal conductivity. A linear dependence relationship of thermal conductivity and electrical conductivity, according to Wiedemann Franz's law, has been validated in Hatch's publication, “Aluminium properties and physical metallurgy”, ASM Metals Park, OH, 1988. second test pieces to a surface polish on each face of 45 mm x 46 mm, in view of the conductivity measurements, with the aid of an abrasive paper with roughness 180. Electrical conductivity measurements were made on the polished faces , using a Foerster Sigmatest 2.069 type measuring device, at 60 kHz.

Table 2, below, represents, for each first test piece, the heat treatment temperature (0C), the duration of heat treatment, the yield point at 0.2% of Rp0.2 (MPa), the resistance to traction (Rm), the elongation at break A (%), as well as the electrical conductivity (MS.m-1). The tensile properties (yield strength, tensile strength, and elongation at break) were determined from the first test pieces, according to the manufacturing direction Z, while the electrical properties (electrical conductivity) were determined in the second test pieces. In Table 2 below, the duration of 0 h corresponds to an absence of heat treatment.

[Table 2]

Without application of a heat treatment, it is evaluated that the mechanical properties are satisfactory. However, the application of an appropriate heat treatment makes it possible to improve the yield strength, the tensile strength, as well as the electrical conductivity. The beneficial effect of heat treatment is attributed to the formation of nanometric Al3Zr precipitates, which leads to a simultaneous increase in yield strength and conductivity. In the absence of heat treatment, a fraction of Zr remains trapped in solid solution.

A notable aspect is that the heat treatment allows the electrical conductivity to be increased very significantly, the latter approaching that of pure aluminum (close to 34 MS/m), while also increasing the mechanical properties with respect to those of pure aluminum.

The parameters that allow obtaining good mechanical properties are the following:

- at 400 0C, the duration being from 1 h to 10 h;

- at 350 °C, the duration being between 10 h and 100 h, knowing that a duration between 10 h and 20 h seems sufficient.

In addition, when a heat treatment is applied, it is preferable that its temperature is less than 500 °C. When obtaining optimum mechanical properties is preferred, the heat treatment temperature is preferably below 450°C and, for example, is between 300°C and 420°C.

When electrical or thermal conduction is favored, the heat treatment temperature is preferably greater than or equal to 350°C or even 400°C, with a duration that can exceed 100 hours, for example, from 90 to 200 hours. It is observed that, when the heat treatment is carried out at 400 0C, the evolution of the tensile mechanical properties (elastic limit, tensile strength), depending on the duration of the treatment, is firstly increasing, and then decreasing. . An optimal duration of heat treatment allows to optimize the tensile mechanical properties. It is comprised from 0.1 h to 10 h, at 400 0C.

The heat treatment is preferably tempering or annealing.

Figure 2 illustrates the tensile properties (axis of the ordinates, which represents the yield point Rp0.2, expressed in MPa) as a function of the properties of thermal conductivity (axis of the abscissas, which represents the thermal conductivity, expressed in MS/m). It is recalled that thermal conduction properties are assumed to be representative of electrical conduction properties. In Figure 2, the percentages indicate the elongation at break. By means of an arrow, the beneficial effect of the heat treatment has been represented, both from the point of view of electrical conductivity and of the elastic limit. In the legend to Figure 2, the term "gross" means an absence of heat treatment.

The relative density of the samples was greater than 99.5 %, which translates into a porosity < 0.5 %, the latter having been estimated by image analysis on a section of polished samples.

A second trial was performed using:

- an alloy 1 as described above;

- an alloy2, whose composition by mass measured by ICP comprised Al; 1.78% Zr; Faith at 1.04%; Yes at 1812 ppm; Cu at 503ppm; impurities < 0.05%, each with an accumulation of impurities < 0.15%.

Test pieces similar to those described in connection with the first test were formed.

The powder used had a particle size essentially ranging from 3 µm to 100 µm, with a median of 41 µm, a 10% quantile of 15 µm, and a 90% quantile of 82 µm.

The Vickers Hv0.2 hardness was characterized, according to the ASTM E384 standard, as well as the electrical conductivity, in parallelepipedic pieces. Hardness and conductivity measurements were made in the absence of heat treatment, as well as after different heat treatments.

Table 3 presents the results of the characterizations. N/A means that the characteristic has not been measured.

[Table 3]

Tests confirm that:

- the presence of Fe significantly improves the mechanical properties;

- The application of a heat treatment improves the mechanical and electrical conduction properties.

Example 2

A second test, similar to Example 1, was carried out using Alloy 2, as described above in relation to Example 1.

The powder used had a particle size essentially ranging from 3 µm to 100 µm, with a median of 41 µm, a 10% quantile of 15 µm, and a 90% quantile of 82 µm.

Test pieces were made by SLM, using a machine of the type EOS M290 SLM (supplier EOS). The laser power was 370 W. The scanning speed was equal to 1250 mm/s. The separation between two adjacent scan lines, usually designated by the term "separation vector", was 0.111 mm. The layer thickness was 60 μm.

As for Example 1, the addition of a heat treatment for up to 100 h at 400 0C or 450 0C, allowed to simultaneously increase the mechanical resistance and the electrical conductivity, with respect to the raw state of relaxation, as illustrated in Fig. Table 4, below, and in Figure 6.

[Table 4]

Alloy 2 allowed to show the positive impact of the addition of Fe on the increase of the elastic limit Rp02, and of the resistance at break Rm (without significant degradation of the electrical conductivity) with respect to alloy 1 of Example 1. This alloy 2 made it possible to reach, after heat treatment, values of Rp02 and Rm not achievable by alloy 1 of Example 1, with Rp02 values greater than 260 MPa, while maintaining an electrical conductivity greater than 24 MS/m, even at 26 MS/m.

Without being limited to theory, it seems that, in parts manufactured by classical procedures, such as machining from blocks obtained by forging, Fe is present in the form of coarse intermetallic structures, with a size ranging up to a few tens of μm. . On the contrary, in the parts manufactured by means of selective laser melting, from alloy 2 of Example 2, Fe is present in the form of nanometric precipitates that do not present any negative impact on the resistance to corrosion, nor on the aptitude from alloy to anodizing. On the contrary, the presence of Fe-based nanometric precipitates seems to present a positive impact on the corrosion performance, leading to lateralized and non-localized corrosion of the parts under test.

Example 3

A third test similar to that of Example 2 was carried out using an alloy 3, whose composition by mass measured by ICP comprised: Al; 1.23% Zr; Faith at 0.94%;

impurities < 0.05%, each with an accumulation of impurities < 0.15%.

The powder used had a particle size essentially ranging from 3 µm to 100 µm, with a median of 37 µm, a 10% quantile of 15 µm, and a 90% quantile of 71 µm.

Test pieces were made by SLM, using a machine of the type EOS M290 SLM (supplier EOS). The laser power was 370 W. The scanning speed was equal to 1250 mm/s. The separation between two adjacent scan lines, usually designated by the term "separation vector", was 0.111 mm. The layer thickness was 60 μm.

As for Example 2, the addition of a heat treatment for up to 100 h at 400 0C, allowed to increase, simultaneously, the mechanical resistance and the electrical conductivity, with respect to the raw state of relaxation, as illustrated in Table 5 below.

[Table 5]

The reduction of the Zr content of alloy 3 with respect to that of alloy 2 (respectively, 1.23% versus 1.78% of Zr) led to a significant increase in the elongation and electrical conductivity values, and this for all the heat treatments after manufacturing, subjected to tests (see Tables 4 and 5 above). Alloy 3 also had a softer as-made condition than Alloy 2: Rp02, respectively, 133 MPa vs. 214 MPa. This softer raw state is advantageous in terms of processability during the SLM procedure, as it allows a significant reduction in residual stresses during part manufacturing. The best mechanical resistances of alloy 3 and alloy 2 were similar, and were obtained for a heat treatment after fabrication, respectively, of 4 h at 400 0C, compared to 1 h at 400 0C. Under these conditions of maximizing mechanical resistance, alloy 3 had the advantage of offering both better elongation and better electrical conductivity.

Example 4

A fourth test, similar to that of Example 2, was carried out using an alloy 4, whose composition by mass measured by ICP comprised: Al; 0.81% Zr; Faith at 1.83%;

impurities < 0.05%, each with an accumulation of impurities < 0.15%.

The powder used had a particle size essentially ranging from 3 µm to 100 µm, with a median of 38 µm, a 10% quantile of 15 µm, and a 90% quantile of 75 µm.

Test pieces were made by SLM, using a machine of the type EOS M290 SLM (supplier EOS). The laser power was 370 W. The scanning speed was equal to 1250 mm/s. The separation between two adjacent scan lines, usually designated by the term "separation vector", was 0.111 mm. The layer thickness was 60 μm.

As for Example 2, the addition of a heat treatment for up to 100 h at 400 0C or 450 0C, allowed to increase, simultaneously, the mechanical resistance and the electrical conductivity, with respect to the raw state of relaxation, as illustrated in Table 6, below. Alloy 4 allowed showing the interest of a reduction in the Zr content associated with an addition of 1.83% of Fe, with respect to alloy 1.

The best mechanical resistances of alloy 4 and alloy 1 were obtained for a heat treatment of 4 h at 400 0C. Under these conditions of maximization of mechanical resistance, alloy 4 presented, with respect to alloy 1, a significant increase in Rp02 and elongation, with a decrease in electrical conductivity, see Table 2 above and Table 6, below. continuation.

[Table 6]

Example 5

A fifth test, similar to that of Example 2, was carried out using an alloy 5, whose composition by mass measured by ICP comprised: Al; 1.39% Zr; 0.32% Cu;

impurities < 0.05%, each with an accumulation of impurities < 0.15%.

The powder used had a particle size essentially ranging from 3 µm to 100 µm, with a median of 27 µm, a 10% quantile of 11 µm, and a 90% quantile of 54 µm.

Test pieces were made by SLM, using a machine of the type EOS M290 SLM (supplier EOS). The laser power was 370 W. The scanning speed was equal to 1250 mm/s. The separation between two adjacent scan lines, usually designated by the term "separation vector", was 0.111 mm. The layer thickness was 60 μm.

As for Example 2, the addition of a heat treatment for up to 100 h at 400 0C or 450 0C, allowed to increase, simultaneously, the mechanical resistance and the electrical conductivity, with respect to the raw state of relaxation, as illustrated in Table 7, below. Alloy 5 made it possible to show the interest of a reduction in the Zr content associated with an addition of 0.32% of Cu with respect to alloy 1. Indeed, alloy 5 had both better mechanical resistance and better elongation than alloy 1, and this for all heat treatments after manufacturing, tested at 350 0C and 400 0C.

The best mechanical resistances of alloy 1 were obtained for a heat treatment of 4 h at 400 0C. Under these conditions, alloy 5 presented, with respect to alloy 1, a significant increase in Rp02 and elongation, associated with a very low decrease in electrical conductivity, see Table 2 above and Table 7 below. Alloy 5 allowed to show the positive impact of the addition of Cu, associated with a reduction of Zr on the increase of the elastic limit Rp02 and of the resistance at break Rm (without significant degradation of electrical conductivity) with respect to alloy 1 from Example 1.

[Table 7]

Example 6

Complementary hot tensile tests were carried out with alloys 3 and 4, described, respectively, in Examples 3 and 4.

In the same manner as described in Example 1, test pieces were constructed in the form of solid cylinders vertical (Z direction) with respect to the base-forming building plate in the (X-Y) plane. The cylinders had a diameter of 11 mm and a height of 46 mm.

These test pieces were made by SLM, using an EOS M290 SLM type machine (EOS supplier), and following 2 different sets of SLM parameters, designated set 1 and set 2, as follows:

Set 1:

• Laser power: 370 W

• Scanning speed: 1250 mm/s

• Separation vector: 0.111 mm

• Layer thickness: 60 μm

set 2:

• Laser power: 370 W

• Scanning speed: 1307 mm/s

• Separation vector: 0.177 mm

• Layer thickness: 60 μm

All the pieces were subjected to a relaxation treatment after manufacturing SLM for 4 hours at 300 0C. Some parts were subjected to a heat treatment after manufacturing at 400°C, the duration of the treatment being between 1 h and 4 h (see Table 8 below). All first parts (with and without heat treatment after fabrication) were machined to form cylindrical tensile specimens similar to those described in Example 1 (see Figure 4 and Table 1 above).

Tensile tests were carried out at high temperature (200 0C), from the tensile specimens obtained following the NF EN ISO 6892-1 (2009-10) standard. The results of these tests are summarized in Table 8, below. For each same condition tested, alloy 4 had better mechanical performance (Rp0.2 and Rm) than alloy 3.

Example 6 made it possible to show the positive impact of the increase in the Fe content associated with a reduction in the Zr content on the mechanical properties at high temperatures (comparison between the performance of alloy 3 and alloy 4).

[Table 8]

According to one embodiment, the method may comprise hot isostatic compression (HIC). The CEC treatment can specifically make it possible to improve the elongation properties and the fatigue properties. Hot isostatic compression can be performed before, after, or instead of heat treatment. Advantageously, the hot isostatic compression is carried out at a temperature of 250 0C to 500 0C, and preferably 300 0C to 450 0C, at a pressure of 50 to 300 MPa (500 to 3000 bar) and for a duration of 0.5 to 50 hours.

The possible heat treatment and/or hot isostatic compression make it possible, in particular, to increase the hardness or the elastic limit and the electrical conductivity of the product obtained. However, it should be noted that, generally, the higher the temperature, the more conductivity (electrical or thermal) is favored, to the detriment of mechanical resistance. According to another embodiment, adapted to structural hardening alloys, a solution can be carried out, followed by quenching and tempering of the formed part, and/or hot isostatic compression. In this case, hot isostatic compression can advantageously replace putting into solution.

However, the process according to the invention is advantageous, since it preferably does not require any treatment of putting into solution, followed by quenching. Putting it into solution can have a harmful effect on the mechanical resistance in certain cases, contributing to an increase in the size of the dispersed systems or of the fine intermetallic phases.

According to one embodiment, the method according to the present invention further comprises, optionally, a machining treatment and/or a chemical, electrochemical or mechanical surface treatment, and/or a tribofinishing. These treatments can be carried out specifically to reduce roughness and/or improve corrosion resistance and/or improve resistance to fatigue crack initiation.

Optionally, it is possible to carry out a mechanical deformation of the part, for example, after additive manufacturing and/or before heat treatment.

Although described in relation to an additive manufacturing method of the SLM type, the procedure can be applied to other additive manufacturing methods of the WAAM type, mentioned in connection with the prior art. Figure 3 represents such an alternative. An energy source 31, in this case a torch, forms an electric arc 32. In this device, the torch 31 is held by a welding robot 33. The part 20 to be manufactured is arranged on a support 10. In this example, the manufactured part is a wall that extends along a transversal axis Z, perpendicular to an XY plane defined by the support 10. Under the effect of the electric arc 12, a filler wire 35 melts to form a Weld. The welding robot is controlled by a digital model M. It moves so that different layers 20 ¹ ... 20 ⁿ are formed, stacked one on top of the other, forming the wall 20, each layer corresponding to a weld bead. Each layer 20 ¹ ...20 ⁿ extends in the XY plane, according to a pattern defined by the digital model M.

The diameter of the filler wire is preferably less than 3 mm. It can be between 0.5 mm and 3 mm, and is preferably between 0.5 mm and 2 mm, even between 1 mm and 2 mm. For example, it is 1.2 mm.

On the other hand, other procedures can be provided, for example, and in a non-limiting manner:

- Selective laser sintering (Selective Laser Sintering or SLS);

- direct metal laser sintering (Direct Metal Laser Sintering or DMLS);

- selective sintering by heating (Selective Heat Sintering or SHS);

- electron beam melting (Electron Beam Melting or EBM);

- laser melting deposition (Laser Melting Deposition);

- direct deposition by contribution of energy (Direct Energy Deposition or DED);

- direct metal deposition (Direct Metal Deposition or DMD);

- direct deposition by laser (Direct Laser Deposition or DLD);

- laser deposition technology (Laser Deposition Technology);

- laser engineering net shapes (Laser Engineering Net Shaping);

- laser cladding technology (Laser Cladding Technology);

- laser freeform manufacturing technology (Laser Freeform Manufacturing Technology or LFMT);

- deposition by laser fusion (Laser Metal Deposition or LMD);

- cold spraying (Cold Spray Consolidation or CSC);

- additive manufacturing by friction (Additive Friction Stir or AFS);

- Spark plasma sintering or ultra-fast sintering (Field Assisted Sintering Technology, FAST or spark plasma sintering); either

- rotary friction welding (Inertia Rotary Friction Welding or IRFW).

The solutions according to the present invention are particularly suitable for the cold spray process (so-called "cold spray"), specifically because of the low hardness of the powder, which facilitates deposition. The part can then be hardened by a hardening anneal (post-heat treatment). The solutions according to the present invention are particularly adapted for applications in the electrical, electronic and heat exchanger fields.

Claims (16)

Yo. Manufacturing process for a part (20), which comprises forming successive metal layers (20 ¹ ...20 ⁿ ), superimposed on each other, each layer being formed by deposition of a filler metal (15, 25). , subjecting the filler metal to a supply of energy, so that it melts and forms, upon solidification, said layer, the procedure being characterized in that the filler metal (15, 25) is an aluminum alloy, which comprises the following alloying elements (% by weight): - Zr: from 0.5 to 2.5%, preferably, according to a first variant, from 0.8 to 2.5%, more preferably from 1 to 2.5%, even more preferably from 1.3 to 2, 5 %; or preferably, according to a second variant, from 0.5 to 2%, more preferably from 0.6 to 1.8%, more preferably from 0.6 to 1.6%, more preferably from 0.7 to 1.5 %, more preferably 0.8 to 1.5%, more preferably 0.9 to 1.5%, even more preferably 1 to 1.4%; - Fe: from 0% to 3%, preferably from 0.5% to 2.5%; preferably, according to a first variant, from 0.8 to 2.5%, preferably from 0.8 to 2%, more preferably from 0.8 to 1.2%; or preferably, according to a second variant, from 1.5 to 2.5%, preferably from 1.6 to 2.4%, more preferably from 1.7 to 2.3%; - optionally, Si: <0.3%, preferably <0.2%, more preferably <0.1%; - optionally, Cu: <0.5%, preferably from 0.05 to 0.5%, preferably from 0.1 to 0.4%; - optionally, Mg: <0.2%, preferably <0.1%, preferably <0.05%; - other alloying elements < 0.1% individually, and in total < 0.5%; - impurities: <0.05% individually, and in total <0.15%; the rest, aluminum. 2. Process according to claim 1, wherein the other elements are chosen from: Cr, V, Ti, Mn, Mo, W, Nb, Ta, Sc, Ni, Zn, Hf, Nd, Ce, Co, La, Ag , Li, Y, Yb, Er, Sn, In, Sb, Sr, Ba, Bi, Ca, P, B, and/or Mischmetal. Process according to any one of the preceding claims, wherein the fraction by mass of each of the other alloying elements is less than 300 ppm, even less than 200 ppm, or even less than 100 ppm. 4. Process according to any one of the preceding claims, wherein: - Zr: from 0.5% to 2.5%; - Faith: > 1 %. 5. Process according to any one of claims 1 to 3, wherein: - Zr: from 0.5% to 2.5%; - Faith: < 1 %. Method according to any one of the preceding claims, comprising, after the formation of the layers (20 ¹ ...20 ⁿ ), that is to say, after the formation of the final piece, an application of a heat treatment. 7. Process according to claim 6, wherein the heat treatment is tempering or annealing. 8. Process according to any one of claims 6 or 7, wherein the heat treatment is carried out: - at a temperature higher than 400°C, in which case the duration of the heat treatment is between 0.1 h and 10 h; - or at a temperature between 300 0C and 400 0C, in which case the duration of the heat treatment is between 0.5 h and 100 h. 9. Process according to any one of claims 6 or 7, wherein the heat treatment is carried out at a temperature greater than or equal to 350°C, even 400°C, or for a duration of 90 to 200 hours, so as to obtain optimal thermal or electrical conductivity. Process according to any one of the preceding claims, which does not comprise any tempering after the formation of the layers, that is to say, after the formation of the final part, or after the heat treatment. 11. Process according to any one of the preceding claims, characterized in that it is carried out at a temperature ranging up to 350°C. 12. Process according to any one of the preceding claims, wherein the filler metal takes the form of a powder (15), whose exposure to a beam (12) of light or charged particles results in a localized melting, followed by by solidification, so that a solid (20 ¹ ...20 ⁿ ) layer is formed. Process according to any one of claims 1 to 11, wherein the filler metal comes from a filler wire (25), whose exposure to a heat source (22) results in localized melting, followed by solidification. , so that a solid (20 ¹ ...20 ⁿ ) layer is formed. 14. Metal part obtained by means of a procedure that is the object of any one of the preceding claims. 15. Powder, intended to be used as a filler material for an additive manufacturing process, characterized in that it is made up of an aluminum alloy, which comprises the following alloy elements (% by weight): - Zr: from 0.5% to 2.5%, preferably, according to a first variant, from 0.8 to 2.5%, more preferably from 1 to 2.5%, even more preferably from 1.3 to 2 ,5 %; or preferably, according to a second variant, from 0.5 to 2%, more preferably from 0.6 to 1.8%, more preferably from 0.6 to 1.6%, more preferably from 0.7 to 1.5 %, more preferably 0.8 to 1.5%, more preferably 0.9 to 1.5%, even more preferably 1 to 1.4%; - Fe: from 0% to 3%, preferably from 0.5% to 2.5%; preferably, according to a first variant, from 0.8 to 2.5%, preferably from 0.8 to 2%, more preferably from 0.8 to 1.2%; or preferably, according to a second variant, from 1.5 to 2.5%, preferably from 1.6 to 2.4%, more preferably from 1.7 to 2.3%; - optionally, Si: <0.3%, preferably <0.2%, more preferably <0.1%; - optionally, Cu: <0.5%, preferably from 0.05 to 0.5%, preferably from 0.1 to 0.4%; - optionally, Mg: <0.2%, preferably <0.1%, preferably <0.05%; - other alloying elements < 0.1% individually, and in total < 0.5%; - impurities: <0.05% individually, and in total <0.15%; the rest, aluminum. Use of a powder according to claim 15, in a manufacturing process chosen from: cold sputtering (CSC), laser fusion deposition (LMD), additive friction manufacturing (AFS), spark sintering with plasma (FAST), or rotary friction welding (IRFW), preferably cold spray (CSC).